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Rare fossil found in North Dakota valley
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The sea turtles were 15-20 feet long, with five to six foot flippers and a rubbery shell. (MPR Photo/Dan Gunderson)
In a dry riverbed in eastern North Dakota, people on their hands and knees carefully uncover rare bones. This river valley was gouged from the earth 10,000 years ago by water from melting glaciers. In the bed of an ancient ocean, scientists found a giant sea turtle. The discovery is from a time and place far removed from the North Dakota wheat fields.

Cooperstown, N.D. — Paleontologist John Hoganson loves coming to this dry river bed.

"Where we're standing is the bed of the ocean -- would have been the bed of the ocean 75 million years ago," says Hoganson, who works for the North Dakota Geological Survey.

Dusty green sage plants dot the landscape, along with a scattering of cactus. A young red tail hawk circles lazily above. Under the thin layer of gray clay lie treasures from another time.

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Image John Hoganson

"Coming out here for me -- and I've been doing this for 20 years -- it's always a thrill to go to a place where you can think back that 75 million years ago this would have been the bottom of the ocean, with sharks swimming in here and these huge turtles," says John Hoganson.

A rough circle about 40 feet in diameter is roped off, and lots of small pink flags are stuck in the ground, each marking the spot where a piece of bone was found on the surface.

Eight people using a variety of hand tools are carefully removing dirt from a small area. A middle-aged man with broad shoulders and a sunburned neck lies on his stomach. He's intently unearthing a small bone with a dental pick.

Peter Mack is a tow truck driver and amateur rock hound, who has been coming to this valley for 30 years to look for arrowheads and fossils. It was here last summer that he stumbled across an interesting bone. He wasn't sure what it was, but he knew it was important because he'd never seen anything like it before.

"I got kind of excited -- probably a little over-excited. It's pretty exciting you know, not finding much for 30 years and then stumbling across something like this. It's pretty good," says Mack.

... Other people sit home and watch Discovery Channel, but we get to do it.
- Amateur paleontologist Jim Daly

Peter Mack's rare find was the jawbone of an Archelon, a giant sea turtle that lived in a shallow sea covering all of North Dakota 75 million years ago. The sea turtles were 15-20 feet long, with five to six-foot flippers and a rubbery shell.

Part of a flipper is partially uncovered, and there's also a flat curved bone about three feet long that may be a rib.

Jim Daly is digging a trench around the bone so it can be encased in plaster to keep it safe while it's hauled to the laboratory in Bismarck, North Dakota. Daly is a retired police officer from Little Canada, Minnesota. He's been on several fossil digs in North Dakota, and Daly is willing to put in long days in the scorching sun for a simple reason.

"Being the first human to see something that's 75 million years old," says Daly. "I picked up fossils when I was young. I've just always been interested in them. Now I have time to go on the digs. I tell people -- other people sit home and watch Discovery Channel. We get to do it."

Paleontologist John Hoganson depends on volunteers like Jim Daly, because he has a small staff and can't afford to hire enough professionals for large excavations.

This is painstaking work, because these bones are fragile and could easily crumble if not handled properly. Progress is measured in fractions of an inch.

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Image The dig site

Hoganson has been digging for fossils in North Dakota for more than 20 years, but still gets a thrill from seeing ancient bones emerge from the earth.

"There's nothing quite like finding a Tyrannosaurus Rex tooth lying on the surface of the earth, or a turtle jaw, or these kind of things," Hoganson says. "Most of the people who come and work with me here -- most of them are volunteers, and they always talk about, 'Wow, I'm the first person to have seen this bone in 75 million years.' There's something about that, yeah."

It will likely take most of the summer to see just how much of the Archelon skeleton is buried here. Only a few Archelon fossils have been discovered around the world. The most complete Archelon was found in South Dakota in the 1970s. John Hoganson hopes the North Dakota find will help scientists develop a better picture of life under the sea 75 million years ago.

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